Extremal Convex Planar Sets

Each convex planar set K has a perimeter C, a minimum width E, an area A, and a diameter D. The set of points (E,C, A^1/2, D) corresponding to all such sets is shown to occupy a cone in the non-negative orthant of R⁴with its vertex at the origin. Its three-dimensional cross section S in the plane D = 1 is investigated. S lies in a rectangular parallelepiped in R³. Results of Lebesgue, Kubota, Fukasawa, Sholander, and Hemmi are used to determine some of the boundary surfaces of S, and new results are given for the other boundary surfaces. From knowledge of S, all inequalities among E, C ,A, and D can be found.     

海洋激光雷达测量海中悬移质

研制了一套采用倍频YAG激光器的小型海洋激光雷达，用于测量海中悬移质浓度，2000年8月28日至9月5日，该系统安装于“东方红Ⅱ”号右舷下甲板，在渤海海区进行海中悬移质浓度现场测量，通过对18个站位的海洋激光雷达数据分析，获得的表层悬移质浓度与同步测量的海中悬移质浓度结果吻合较好。     

Electron–hole recombination luminescence in LiYF4:U single crystal

Photoluminescence (PL), photostimulated luminescence (PSL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) studies were carried out on LiYF₄:U⁴⁺ and pure LiYF₄ crystals. The PL and EPR investigations have identified the presence of Eu³⁺, Tb³⁺ and Gd³⁺ ions in both of these crystals possibly due to their existence in the starting materials. The luminescence observed during afterglow, PSL and TSL revealed that emission occurs at wavelength positions 382, 413, 437 and 544 nm, which are characteristic of Tb³⁺ ions. The present investigations using PSL and TSL in combination with PL studies before and after gamma irradiation have revealed that selective energy transfer to Tb³⁺ ions occurs during electron–hole recombination processes like PSL and TSL. Even though other luminescent ions (U⁴⁺ and Eu³⁺) are present in the system and U⁴⁺/U³⁺ ions are participating in electron capture/release processes, the selective energy transfer results in Tb³⁺ ions acting as luminescence centers.     

斐索梯度折射率光纤透镜传感实验

采用LD泵浦的单纵模Nd：YVO4倍频激光器、梯度折射率光纤透镜等器件构成斐索梯度折射率光纤透镜传感实验仪．本文介绍了实验装置和实验原理，并给出了实验结果。     

Spreading Code Design Using a Global Optimization Method

The performance of a code division multiple access system depends on the correlation properties of the employed spreading code. Low cross-correlation values between spreading sequences are desired to suppress multiple access interference and to improve bit error performance. An auto-correlation function with a distinct peak enables proper synchronization and suppresses intersymbol interference. However, these requirements contradict each other and a trade-off needs to be established. In this paper, a global two dimensional optimization method is proposed to minimize the out-of-phase average mean-square aperiodic auto-correlation with average mean-square aperiodic cross-correlation being allowed to lie within a fixed region. This approach is applied to design sets of complex spreading sequences. A design example is presented to illustrate the relation between various correlation characteristics. The correlations of the obtained sets are compared with correlations of other known sequences.     

A New Cytotoxic Acetogenin from the Seeds of Annona squamosa

A New Annonaceous acetogenin,squamostolide(1),was isolated from the seeds of Annona squamosa.Its structure was elucidated based on spectroscopic methods and comparison with known compounds.It is the first example of Annonaceous acetogenin with each of the two ends of the aliphatic chain bearing a γ-lactone.Thenew compound exhibited cytotoxic activity in vitro against bel-7402 and CNE2 human tumor cell lines.     

The Synthesis of Glycoglycerolipids

A convenient synthetic route was developed for the synthesis of the novel glycolipids: 1,2-di-O-acyl-3-O-(2‘-acylamide-2‘-denxy-ct-D-glucopyranosyl)-sn-glycerols. 10 new compounds of glycolipids with different acyl groups were obtained.     

数字全息中再现像分离问题的研究

详细分析了数字全息的再现像分离条件,指出数字全息和普通全息的再现像分离条件之间的区别,同时也讨论了再现条件对数字全息记录光路的要求,同时给出一种能部分避免再现像重叠的处理方法,并做出相应的实验验证.     

Decay distribution of spontaneous emission from atoms in one-dimensional photonic crystal

Spontaneous emission behavior from atoms (or molecules) in one-dimensional photonic crystal with a defect is investigated. Taken all the TE and TM modes into account, the normalized spontaneous emission rate of the atom is calculated as a function of the position of the atom in the crystal. Results for both nonabsorbing dielectric structure and absorbing dielectric structure are presented. With the increase of the thickness of the defect in which the atoms are embedded, the oscillations of the spontaneous emission rate versus the position of the atom become dense and the lifetime distribution becomes narrow and sharp. The PC effect may lead to the coexistence of both accelerated and inhibited decay processes.     

Simple Entanglement Measure for Multipartite Pure States

A simple entanglement measure for multipartite pure states is formulated based on the partial entropy of a series of reduced density matrices. Use of the proposed new measure to distinguish disentangled, partially entangled, and maximally entangled multipartite pure states is illustrated.